1. Field of the Invention
The present invention relates to weighing equipment for weighing a load, which is included in a mechanical system with a natural frequency of oscillation which depends on the size of the load, comprising a transducer influeced by the load and arranged to emit a signal commensurate to the weight of the load.
2. The Prior Art
A typical field of use for an equipment of this kind is in a so-called crane scale. The equipment is then built into a crane, for example an overhead crane, and is used for indicating the weight of the load. The transducer may be, for example, a strain gauge or alternatively a magnetoelastic force transducer. In the cases it is often desirable to obtain a quick and exact reading of the weight of the load. However, obtaining such a quick and reliable reading has proved to offer serious problems, because the load and the wires in which the load is suspended together form a mechanical oscillating system. The load will perform vertical oscillations with a frequency which is determined by the mass of the load and the elasticity of the wires. These oscillations give rise to such strong variations in the force influencing the transducer that it becomes impossible to obtain a sufficiently exact reading of the weight of the load within a reasonable time. The frequency of the oscillation will in all typical cases be very low, for example of the order of magnitude of 2-10 Hz. Conventional filters are impractically slow, and further give rise to a considerable delay upon changes in the load. One further problem is that the load is normally variable, which means that the frequency of the oscillation may vary within relatively wide intervals.